Flame retardant thermoplastic resin composition

ABSTRACT

The present invention relates to a flame retardant polycarbonate thermoplastic resin composition that comprises a polycarbonate resin, a rubber modified vinyl-grafted copolymer, a phosphorous mixture of a cyclic phosphazene oligomer compound and a phosphate ester morpholide compound or a phosphoric acid ester as a flame retardant, and, optionally, a fluorinated polyolefin resin, which has good flame retardancy, heat resistance, mechanical strength, impact strength, heat stability, processability, and appearance.

This application is a continuation in part of Ser. No. 10/489,545 filedMar. 12, 2004 which was a National Stage of International ApplicationNo. PCT/KR01/01891, filed Nov. 7, 2001, published in English under PCTArticle 21(2) and now abandoned. This application is also a continuationin part of Ser. No. 10/488,449 filed Mar. 3, 2004 now U.S. Pat. No.7,094,818 which was a National Stage of International Application No.PCT/KR01/01890, filed Nov. 7, 2001, published in English under PCTArticle 21(2) and now abandoned.

FIELD OF THE INVENTION

The present invention relates to a polycarbonate thermoplastic resincomposition with good flame retardancy, heat resistance and mechanicalproperties. More particularly, the present invention relates to a flameretardant polycarbonate thermoplastic resin composition that comprises apolycarbonate resin, a rubber modified vinyl-grafted copolymer, aphosphorous compound mixture of a cyclic phosphazene oligomer Compoundand a phosphate ester morpholide compound or phosphoric acid ester as aflame retardant, and a fluorinated polyolefin resin, which has goodflame retardancy, heat resistance, mechanical strength, impact strength,heat stability, processability, and appearance.

BACKGROUND OF THE INVENTION

To improve flame retardancy of thermoplastic resin composition is amajor target to the research and development of the resin for a longtime. The flame retardancy is measured by the UL-94 test method ofUnderwriters Laboratory. In this flame retardancy test, if the specimenis flamed out within 10 seconds after flaming and if the total flame outtime is within 50 seconds when five specimens are flamed twice, theresin composition can obtain V-0 degree of flame retardancy.

A blend of a polycarbonate resin and a styrene-containing copolymer is aresin composition which has improved processability maintaining the goodnotched impact strength. The polycarbonate resin composition shouldfurther have good flame retardancy as well as high mechanical strengthbecause the resin composition are applied to electric or electronicgoods, automobile parts, office supplies, etc.

To provide the polycarbonate resin with good flame retardancy, ahalogen-containing flame retardant and/or an antimony-containingcompound were used.

However, the disadvantages could be observed that the halogen-containingcompound results in the corrosion of the mold itself by the hydrogenhalide gases released during the molding process and is fatally harmfuldue to the toxic gases liberated in case of fire. Especially, since thepolybromodiphenyl ether, mainly used for a halogen-containing flameretardant, can produce toxic gases such as dioxin or furan duringcombustion, flame retardants which are prepared without ahalogen-containing compound have become a major concern in this field.Accordingly, It is a trend to prepare a resin composition using ahalogen-free phosphorous compound.

Phosphorous compounds are a representative halogen-free flame retardant.The phosphorous compounds include monophosphate such astriphenylphosphate and tricresylphosphate, and oligomeric phosphate suchas resorcinol bis(diphenylphosphate), hydroquinonebis(diphenylphosphate) and bisphenol-A bis(diphenylphosphate). However,as the halogen-free flame retardant shows a poorer flame retardancy thanthe halogen-containing flame retardant, an excess amount of halogen-freeflame retardant should be used to obtain the same degree of flameretardancy. If an excess amount of the flame retardant is used, theimpact strength and heat resistance of the resin composition can becomeseverely deteriorated.

Japanese Patent Laid-open No. 2000-154277 discloses a thermoplasticresin composition using phosphoric acid amide as a flame retardant,which improves processability of the resin and hydrolysis resistance ofthe flame retardant. However, particular phosphoric acid amides causepoor hydrolysis resistance of the flame retardant resin composition.Further, in certain phosphorous acid amides, the flame retardancy andimpact strength are severely decreased and the flame retardant becomesvolatile to cover the surface of the molded article, so called, to occurjuicing phenomenon.

Japanese Patent Laid-open No. 6-100,785 discloses a flame retardantresin composition which comprises a thermoplastic resin, a phosphatecompound, and a silicon resin or a polyphosphazene to prevent fromdripping of the resin during combustion. However, the Japanese patentapplication does not disclose that the flame retardancy of the resincomposition had been improved.

EP 0 728 811 A2 discloses a thermoplastic resin composition comprisingan aromatic polycarbonate, a graft copolymer, a copolymer and aphosphazene. The European patent teaches that no dripping occurs duringcombustion by using a phosphazene as a flame retardant even though anadditional anti-dripping agent is not employed, and that the resincomposition has excellent heat resistance and impact strength. However,the resin composition of the European patent has a poor processabilitydue to the poor flowability by using the phosphazene, and causes blackstripes and/or black lines on the surface of the molded article due todegradation of the resin or flame retardants when an excess stress isapplied to the article during molding. In the European patent usingphosphazene as a flame retardant, mechanical strength such as flexuralstrength and flexural modulus becomes deteriorated, and more flameretardants should be used to maintain a certain degree of flameretardancy.

WO 00/09518 and WO 99/19383 disclose methods of preparing a cross-linkedlinear or cyclic phenoxy phosphazene and a thermoplastic resincomposition using such phosphazene compounds. According to the patentapplications, the cross-linked phenoxy phosphazene does not deterioratethe mechanical properties of the resin composition when applied, becausethe phosphazene has a high melting point and lower volatility. However,the resin composition of the patent applications has a poorprocessability due to the poor flowability by using the phosphazene, andcauses black stripes and/or black lines on the surface of the moldedarticle due to degradation of the resin or flame retardants when anexcess stress is applied to the article during molding. In the patentapplications using phosphazene as a flame retardant, mechanical strengthsuch as flexural strength and flexural modulus becomes deteriorated.

Any section of the Background of the Invention in parent U.S. Pat. No.7,094,818 is herein incorporated by reference.

The present inventors have developed a flame retardant thermoplasticresin compositions which have good balance of physical properties suchas impact strength, heat resistance, heat stability, processability andappearance. The invention includes compositions which comprise apolycarbonate resin, a rubber modified vinyl-grafted copolymer, a vinylcopolymer, a phosphorous compound mixture of a cyclic phosphazeneoligomer compound and a phosphate ester morpholide compound as a flameretardant and a fluorinated polyolefin resin. The invention alsoincludes compositions which comprise a polycarbonate resin, a rubbermodified vinyl-grafted copolymer, a vinyl copolymer, an oligomer typecyclic phosphazene compound and a phosphoric acid ester as a flameretardant and a fluorinated polyolefin resin,

Other embodiments of the invention include compositions that do notcontain the fluorinated polyolefin resin in situations where theproperties provided by the resin are not required or can be provided byother materials or methods.

The filing of this application and the content thereof is not and is notto be construed as any agreement or concession to any rejection orobjection made in the parent applications. This application is beingfiled to preserve Applicants' rights in the inventions, including butnot limited to, inventions disclosed in the parent U.S. applications,the international applications, and the foreign priority applications inview of inconsistency in the application of the rules/law relating topatents in the U.S.

SUMMARY OF THE INVENTION

A flame retardant thermoplastic resin composition according to thepresent invention comprises:

-   -   (A) about 45 to 95 parts by weight of a polycarbonate resin;    -   (B) about 1 to 50 parts by weight of a rubber modified        vinyl-grafted copolymer prepared by graft-polymerizing (b₁)        about 5 to 95 parts by weight of a monomer mixture of about 50        to 95% by weight of styrene, α-methylstyrene, halogen- or        alkyl-substituted styrene, C₁₋₈ methacrylic acid alkyl ester,        C₁₋₈ acrylic acid alkyl ester, or a mixture thereof and about 5        to 50% by weight of acrylonitrile, methacrylonitrile, C₁₋₈        methacrylic acid alkyl ester, C₁₋₈ acrylic acid alkyl ester,        maleic acid anhydride, C₁₋₄ alkyl- or phenyl N-substituted        maleimide or a mixture thereof onto (b₂) about 5 to 95 parts by        weight of a rubber polymer selected from the group consisting of        butadiene rubber, acryl rubber, ethylene-propylene rubber,        styrene-butadiene rubber, acrylonitrile-butadiene rubber,        isoprene rubber, copolymer of ethylene-propylene-diene (EPDM),        polyorganosiloxane-polyalkyl (meth)acrylate rubber or a mixture        thereof;    -   (C) about 0 to 50 parts by weight of a vinyl copolymer        polymerized with (c₁) about 50 to 95% by weight of styrene,        α-methylstyrene, halogen- or alkyl-substituted styrene, C₁₋₈        methacrylic acid alkyl ester, C₁₋₈ acrylic acid alkyl ester, or        a mixture thereof and (c₂) about 5 to 50% by weight of        acrylonitrile, methacrylonitrile, C₁₋₈ methacrylic acid alkyl        ester, C₁₋₈ acrylic acid alkyl ester, maleic acid anhydride,        C₁₋₄ alkyl- or phenyl N-substituted maleimide or a mixture        thereof;    -   (D) about 1 to 30 parts by weight of a phosphorous mixture as a        flame retardant, per 100 parts by weight of (A)+(B)+(C), of (d₁)        about 1 to 50% by weight of a cyclic phosphazene oligomer        compound or their mixture represented by the following Formula        (I);

-   -   -   where R₁ is alkyl, aryl, alkyl substituted aryl, aralkyl,            alkoxy, aryloxy, amino or hydroxyl, k and m are an integer            from 1 to 10, R₂ is dioxyarylene group of C₆₋₃₀ or a            derivative thereof, and n is 0 or an integer representing            the number of repeating unit and the average value of n in            the phosphazene mixture is 0.3 to 3; and        -   about 99 to 50% by weight of (d₂) or (D₂) wherein (d₂) is a            phosphate ester morpholide compound represented by the            following Formula (II);

-   -   -   where R₃ is a C₆₋₂₀ aryl group or an alkyl-substituted C₆₋₂₀            aryl group, R₄ is a C₆₋₃₀ arylene group or an            alkyl-substituted C₆₋₃₀ arylene group, l is 1 or 2, and x            and y are 0 or integers representing the number of            corresponding units and the average value of (x+y) in the            mixture of phosphate ester morpholide compounds is 0 to 5;            and (D₂) is a phosphoric acid ester; and,

    -   (E) about 0.05 to 5.0 parts by weight of a fluorinated        polyolefin resin with average particle size of about 0.05 to        1000 μm and density of about 1.2 to 2.3 g/Cm³, per 100 parts by        weight of (A)+(B)+(C).

DETAILED DESCRIPTION OF THE INVENTION

A flame retardant thermoplastic resin composition according to thepresent invention comprises (A) about 45 to 95 parts by weight of apolycarbonate resin, (B) about 1 to 50 parts by weight of a rubbermodified vinyl-grafted copolymer, (C) about 0 to 50 parts by weight of avinyl copolymer, (D) about 1 to 30 parts by weight of a phosphorousmixture of a cyclic phosphazene oligomer and a phosphate estermorpholide, or phosphoric acid ester as a flame retardant, per 100 partsby weight of (A)+(B)+(C), and, optionally, (E) about 0.05 to 5.0 partsby weight of a fluorinated polyolefin resin per 100 parts by weight of(A)+(B)+(C)

(A) Polycarbonate Resin

The polycarbonate resin is prepared by reacting a diphenol representedby the following formula (I) with a phosgene, a halogen formate or acarboxylic acid diester:

where A is a single bond, a C₁₋₅ alkylene group, a C₁₋₅ alkylidenegroup, a C₅₋₆ cycloalkylidene group, S or SO₂.

The examples of the diphenol include hydroquinone, resorcinol,4,4′-dihydroxydiphenol, 2,2-bis-(4-hydroxyphenyl)-propane,2,4-bis-(4-hydroxyphenyl)-2-methylbutane,1,1-bis-(4-hydroxyphenyl)-cyclohexane,2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, and2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane. More preferablediphenols are 2,2-bis-(4-hydroxyphenyl)-propane,2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane, and1,1-bis-(4-hydroxyphenyl)-cyclohexane, and the most preferable diphenolis 2,2-bis-(4-hydroxyphenyl)-propane called ‘bisphenol A’.

In the present invention it is preferable that the polycarbonate resin(A) has a weight average molecular weight (M_(w)) of about 10,000 to200,000, more preferably about 15,000 to 80,000.

A polycarbonate with branched chains may also be preferably used. Inparticular a compound with 3 valences or above may be added in an amountof about 0.05 to 2 mol % per the total moles of the diphenol to be used.A homopolymer of polycarbonate, a copolymer of polycarbonate or amixture thereof may be used in this invention. Some portion of thepolycarbonate resin may be replaced with an aromatic polyester-carbonateresin that is obtained by polymerization in the presence of an esterprecursor, such as difunctional carboxylic acid. The polycarbonate resinis used in an amount of about 45 to 95 parts by weight as per 100 partsby weight of the flame retardant thermoplastic resin compositionaccording to the present invention. The section relating to thepolycarbonate resin in parent U.S. Pat. No. 7,094,818 is hereinincorporated by reference.

(B) Rubber Modified Vinyl-Grafted Copolymer

The rubber modified vinyl-grafted copolymer according to the presentinvention is known in the art. The rubber modified vinyl-graftedcopolymer include, but are not limited to, those prepared bygraft-polymerizing (b₁) about 5 to 95 parts by weight of a monomermixture of about 50 to 95% by weight of styrene, α-methylstyrene,halogen- or alkyl-substituted styrene, C₁₋₈ methacrylic acid alkylester, C₁₋₈ acrylic acid alkyl ester, or a mixture thereof and about 5to 50% by weight of acrylonitrile, methacrylonitrile, C₁₋₈ methacrylicacid alkyl ester, C₁₋₈ acrylic acid alkyl ester, maleic acid anhydride,C₁₋₄ alkyl- or phenyl N-substituted maleimide or a mixture thereof onto(b₂) about 5 to 95 parts by weight of a rubber polymer selected from thegroup consisting of butadiene rubber, acryl rubber, ethylene-propylenerubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber,isoprene rubber, copolymer of ethylene-propylene-diene (EPDM),polyorganosiloxane-polyalkyl(meth)acrylate rubber or a mixture thereof.

The C₁₋₈ methacrylic acid alkyl ester is obtained from methacrylic acidand monohydric alcohol with 1 to 8 carbon atoms and the C₁₋₈ acrylicacid alkyl ester from acrylic acid and monohydric alcohol with 1 to 8carbon atoms. The examples of the acid alkyl ester include methacrylicacid methyl ester, methacrylic acid ethyl ester, acrylic acid methylester, acrylic acid ethyl ester, and methacrylic acid propyl ester.Methacrylic acid methyl ester is the most preferable. Other monomerssuitable for inclusion in the monomer mixture can be readily determinedby one skilled in the art.

Preferable examples of the rubber modified vinyl-grafted copolymer aregrafted-polymers obtained by graft polymerizing a mixture of styrene andacrylonitrile, and, optionally, (meth)acrylic acid alkyl ester ontobutadiene rubber, acryl rubber or styrene-butadiene rubber, or by graftpolymerizing (meth)acrylic acid alkyl ester onto butadiene rubber, acrylrubber or styrene-butadiene rubber. The most preferable examples of therubber modified vinyl-grafted copolymer are a grafted-polymer that amixture of styrene and acrylonitrile is grafted onto butadiene rubber,which is called acrylonitrile-butadiene-styrene (ABS) resin, and agrafted-polymer of MBS resin.

The rubber polymer to prepare the rubber modified vinyl-graftedcopolymer has preferably an average particle size of about 0.05 to 4.0μm considering the impact strength and appearance.

The rubber modified graft copolymer according to the present inventioncan be prepared through a conventional polymerization process such asemulsion, suspension, solution or bulk process. However, the copolymercan be preferably prepared through the emulsion or bulk process in whichvinyl monomers are added to the rubber polymer using an initiator.

The rubber modified vinyl-grafted copolymer is used in an amount ofabout 1 to 50 parts by weight as per 100 parts by weight of the flameretardant thermoplastic resin composition according to the presentinvention.

(C) Vinyl Copolymer

The vinyl copolymer of the present invention is a copolymer that ispolymerized with (c₁) about 50 to 95% by weight of styrene,α-methylstyrene, halogen- or alkyl-substituted styrene, C₁₋₈ methacrylicacid alkyl ester, C₁₋₈ acrylic acid alkyl ester, or a mixture thereofand (c₂) about 5 to 50% by weight of acrylonitrile, methacrylonitrile,C₁₋₈ methacrylic acid alkyl ester, C₁₋₈ acrylic acid alkyl ester, maleicacid anhydride, C₁₋₄ alkyl- or phenyl N-substituted maleimide or amixture thereof. A mixture of the copolymers may be used as thecomponent (C).

The C₁₋₈ methacrylic acid alkyl ester is obtained from methacrylic acidand monohydric alcohol with 1 to 8 carbon atoms and the C₁₋₈ acrylicacid alkyl ester from acrylic acid and monohydric alcohol with 1 to 8carbon atoms. The examples of the acid alkyl ester include methacrylicacid methyl ester, methacrylic acid ethyl ester, acrylic acid methylester, acrylic acid ethyl ester, and methacrylic acid propyl ester.Methacrylic acid methyl ester is the most preferable.

The vinyl copolymer can be produced as by-products when preparing therubber modified vinyl-grafted copolymer (B). The by-products are mostlyproduced when an excess of monomers are grafted onto a small amount ofrubber polymer or when a chain transfer agent is used in excess. Theamount of the vinyl copolymer to be used in this invention does notinclude the amount of the by-products that might be produced duringpreparation of the rubber modified vinyl-grafted copolymer (B).

The preferable examples of the vinyl copolymer are a copolymer ofstyrene and acrylonitrile, a copolymer of α-methylstyrene andacrylonitrile, and a copolymer of styrene, α-methylstyrene andacrylonitrile. The vinyl copolymer is preferably prepared by emulsion,suspension, solution or bulk process, and has a weight average molecularweight (M_(w)) of about 15,000 to 200,000.

Another preferable examples of the vinyl copolymer (C) are a copolymerprepared from a mixture of methacrylic acid methyl ester monomers andoptionally acrylic acid methyl ester monomers. The vinyl copolymer ispreferably prepared by emulsion, suspension, solution or bulk process,and has a weight average molecular weight (M_(w)) of about 20,000 to250,000.

A further preferable example of the vinyl copolymer is a copolymer ofstyrene and maleic acid anhydride, which is prepared by a continuousbulk process or a solution process. The maleic acid anhydride ispreferably used in the amount of about 5 to 50% by weight. The copolymerof styrene and maleic acid anhydride has a weight average molecularweight (M_(w)) of about 20,000 to 200,000 and an intrinsic viscosity ofabout 0.3 to 0.9.

The styrene for preparation of the component (C) in this invention canbe replaced with p-methylstyrene, vinyltoluene, 2,4-dimethylstyrene orα-methylstyrene.

The vinyl copolymer is used in an amount of about 0 to 50 parts byweight as per 100 parts by weight of the flame retardant thermoplasticresin composition according to the present invention. The sectionrelating to the vinyl copolymer (C) in parent U.S. Pat. No. 7,094,818 isherein incorporated by reference.

(D) Phosphorous Compound Mixture of Cyclic Phosphazene Oligomer andPhosphate Ester Morpholide or Phosphoric Acid Ester

The mixture of phosphorous compound is a mixture of (d₁) about 1 to 50%by weight of a cyclic phosphazene oligomer and (d₂) about 99 to 50% byweight of a phosphate ester morpholide. In another embodiment of theinvention, the mixture of phosphorous compound is a mixture of (d₁)about 1 to 50% by weight of a cyclic phosphazene oligomer and (D₂) about99 to 50% by weight of a phosphoric acid ester

(d₁) Cyclic Phosphazene Oligomer

The cyclic phosphazene oligomer is an oligomer type compound or theirmixture of the cyclic phosphazene linked with a linking group having aR₂ group, which is represented as following Formula (I):

where R₁ is alkyl, aryl, alkyl substituted aryl, aralkyl, alkoxy,aryloxy, amino or hydroxyl, k and m are an integer from 1 to 10, R₂ isdioxyarylene group of C₆₋₃₀ or a derivative thereof, and n is 0 or aninteger representing the number of repeating unit and the average valueof n in the mixture of phosphazene compound is 0.3 to 3. The alkoxy andaryloxy groups may be substituted with alkyl, aryl, amino, hydroxyl etc.

In Formula (I), when cyclic phosphazenes of n+1 monomers are linked, theoligomer of cyclic phosphazene is obtained, which has a number averagedegree of polymerization of n.

It is preferable that the mixture of cyclic phosphazene oligomer has anumber average degree of polymerization (n) of 0.3 to 3. In the presentinvention, cyclic phosphazene oligomers having n value of 0 to 10 may bepreferably used in single or in combination as a mixture. The cyclicphosphazene oligomers may be mixed before or after polymerization. Thecyclic phosphazene oligomers may have a branched chain.

In Formula (I), the more preferable groups of R₁ are alkoxy, phenoxy andaryloxy, and the most preferable groups of R₁ is phenoxy.

The preferable groups of R₂ are a derivative from catechol, resorcinol,hydroquinone, or the bisphenylenediol of the following formula:

where Y is alkylene of C₁₋₅, alkylidene of C₁₋₅, cycloalkylidene ofC₅₋₆, S or SO₂, and z is 0 or 1.

The cyclic phosphazene oligomer of the present invention can be preparedthrough a conventional method which is not limited. The following methodfor preparation can be appropriately adopted.

Alkyl alcohol or aryl alcohol reacts with alkali metal hydroxide such assodium hydroxide and lithium hydroxide to prepare alkali metal alkylateor alkali metal arylate. In the same manner, diol with R₂ group reactswith alkali metal hydroxide to prepare alkali metal diarylate. Cyclicdichlorophosphazene reacts with a mixture of the alkali metal alkylateor alkali metal arylate and the alkali metal diarylate, and theresulting solution reacts further with the alkali metal alkylate oralkali metal arylate to obtain the cyclic phosphazene oligomer accordingto the present invention.

(d₂) Phosphate Ester Morpholide

The phosphate ester morpholide is represented by the following Formula(II). The phosphate ester morpholide may be used in single or incombination as a mixture.

where R₃ is a C₆₋₂₀ aryl group or an alkyl-substituted C₆₋₂₀ aryl group,R₄ is a C₆₋₃₀ arylene group or an alkyl-substituted C₆₋₃₀ arylene group,l is 1 or 2, and x and y are 0 or integers representing the number ofcorresponding units and the average value of (x+y) in the mixture ofphosphate ester morpholide compounds is 0 to 5.

In Formula (II), preferably R₃ is a phenyl group or an alkyl-substitutedphenyl group where the alkyl is methyl, ethyl, isopropyl, t-butyl,isobutyl, isoamyl or t-amyl, preferably methyl, ethyl, isopropyl ort-butyl, and R₄ means preferably a C₆₋₃₀ arylene group or analkyl-substituted C₆₋₃₀ arylene group which is a derivative fromresorcinol, hydroquinone or bisphenol-A.

The methods of preparation of the oligomeric phosphate ester morpholidecompound are not limited, but the compound is generally prepared byreacting phosphorus oxychloride (POCl₃) with aromatic alcohol with a R₃group and morpholine at 50-200° C. in the presence of a catalyst by aconventional process to obtain arylmorpholino-chlorophosphate. Then thearylmorpholino-chlorophosphate reacts with dihydroxy arylene compoundwith a R₄ group at 70-220° C. in the presence of a catalyst to obtainthe oligomeric phosphate ester morpholide compound. In another way, theoligomeric phosphate ester morpholide compound can be prepared byreacting phosphorus oxychloride with dihydroxy arylene compound with aR₄ group, and then reacting the product with aromatic alcohol with a R₃group. Further, the oligomeric phosphate ester morpholide compound canbe prepared by reacting the compounds simultaneously.

The catalyst for preparing the phosphate ester morpholide oligomerincludes a metal chloride such as aluminum trichloride (AlCl₃),magnesium chloride (MgCl₂) and zinc chloride (ZnCl₂). Further, atertiary amine such as triethyl amine can be added to remove hydrogenchloride gas which is formed during the reaction process.

In the process for preparing the phosphate ester morpholide oligomer, ifthe phosphorus oxychloride (POCl₃) is reacted with an excess of aromaticalcohol with a R₃ group and morpholine, monophosphate ester morpholidewith x=y=0 can be obtained, and the amount of the monophosphate estermorpholide with x=y=0 can be controlled by adjusting the processconditions. The oligomeric phosphate ester morpholide compound may beused without or after purification.

(D₂) Phosphoric Acid Ester

The phosphoric acid ester is represented by the following Formula (IV).The phosphoric acid ester may be used in single or in combination as amixture.

where R₃, R₄, R₅ and R₇ are a C₆₋₂₀ aryl group or an alkyl-substitutedC₆₋₂₀ aryl group, respectively, preferably a phenyl group or analkyl-substituted phenyl group in which alkyl is methyl, ethyl,isopropyl, t-butyl, isobutyl, isoamyl or t-amyl, preferably methyl,ethyl, isopropyl or t-butyl; R₅ is a C₆₋₃₀ arylene group or analkyl-substituted C₆₋₃₀ arylene group, preferably resorcinol,hydroquinone or bisphenol-A; and l means the number of repeating unitsand the average value of l in the phosphate mixture is 0 to 3.

In the present invention, it is preferable to use an oligomer typephosphoric acid ester that is a derived from a C₆₋₃₀ arylene group andhas an average value of l of about 0 to 3. The oligomer type phosphoricacid ester is a mixture of oligomers in which l is 0, 1, 2 and 3,respectively. The oligomer type phosphoric acid esters are mixed beforeor after polymerization.

The representative examples of the phosphoric acid ester with l=0 aretri(alkylphenyl)phosphate, di(alkylphenyl)monophenylphosphate,diphenylmono(alkylphenyl)phosphate and triphenylphosphate. Thephosphoric acid ester can be used in single or in combination as amixture. The section relating to the phosphoric acid ester in U.S. Pat.No. 7,094,818 is herein incorporated by reference.

About 1 to 30 parts by weight of a phosphorous mixture of (d₁) about 1to 50% by weight of a cyclic phosphazene oligomer compound and about 99to 50% by weight of (d₂) or (D₂) are used per 100 parts by weight of(A)+(B)+(C).

(E) Fluorinated Polyolefin Resin

The examples of the fluorinated polyolefin resin arepolytetrafluoroethylene, polyvinylidenefluoride,tetrafluoroethylene/vinylidenefluoride copolymer,tetrafluoroethylene/hexafluoropropylene copolymer, andethylene/tetrafluoroethylene copolymer. The fluorinated polyolefin resinmay be used in single or in combination as a mixture.

The fluorinated polyolefin resin functions to form a fibrillar networkwhen the resin composition containing the fluorinated polyolefin resinis extruded, resulting to increase the flow viscosity and to increasethe shrinkage during combustion so as to prevent the dripping phenomena.The fluorinated polyolefin resin may be omitted if the propertiesprovided by the resin are not required or if the properties can beobtained by other materials and/or methods of preparing the compositionscontaining of (A), (B), and (D) as described previously.

The fluorinated polyolefin resin (E) according to the present inventionis prepared by a conventional process, for example, the resin isprepared in an aqueous solvent at 7˜71 kg/cm² and 0˜200° C., preferably20˜100° C., in the presence of a free radical forming catalyst such assodium-, potassium-, or ammonium-peroxydisulphate.

The fluorinated polyolefin resin is used in emulsion state or in powderstate. In case using in emulsion state, dispersion of the fluorinatedpolyolefin resin is good, but the process will be somewhat complicated.Accordingly, if the fluorinated polyolefin resin could be uniformlydispersed in the entire resin composition to form the fibrillar networkstructure, it is preferable to use the fluorinated polyolefin resin inpowder state.

The fluorinated polyolefin resin has preferably average particle size ofabout 0.05 to 1000 μm and density of about 1.2 to 2.3 g/cm³.

The fluorinated polyolefin resin is used in an amount of about 0.05 to5.0 parts by weight as per 100 parts by weight of (A)+(B)+(C) of theflame retardant thermoplastic resin composition according to the presentinvention.

Other additives may be contained in the resin composition of the presentinvention. The additives include an additional flame retardant, alubricant, a releasing agent, an anti-dripping agent, an impactmodifier, a plasticizer, a heat stabilizer, an oxidation inhibitor, alight stabilizer, a compatibilizer and the like. An inorganic fillersuch as talc, silica, mica, glass fiber, an organic or inorganic pigmentand/or dye can be added too. The additives are employed in an amount ofabout 0 to 60 parts by weight as per 100 parts by weight of (A)+(B)+(C)of the flame retardant thermoplastic resin composition, preferably about1 to 40 parts by weight.

The flame retardant thermoplastic resin composition according to thepresent invention can be prepared by a conventional method. All thecomponents and additives are mixed together and extruded through anextruder and are prepared in the form of pellets.

The flame retardant thermoplastic resin composition according to thepresent invention can be applied to electric or electronic goods,automobile parts, office supplies, etc which require good flameretardancy, weld-line strength and impact strength.

The invention may be better understood by reference to the followingexamples which are intended for the purpose of illustration and are notto be construed as in any way limiting the scope of the presentinvention. In the following examples, all parts and percentage are byweight unless otherwise indicated.

EXAMPLES

The components to prepare flameproof thermoplastic resin compositions inExamples 1-6 and Comparative Examples 1-7 are as follows

(A) Polycarbonate Resin

Bisphenol-A with a weight average molecular weight (M_(w)) of about25,000 was used as polycarbonate resin.

(B) Rubber Modified Vinyl-Grafted Copolymer

(B₁) 50 parts of butadiene rubber latex, 36 parts of styrene, 14 partsof acrylonitrile and 150 parts of deionized water were mixed. To themixture, 1.0 parts of potassium oleate, 0.4 parts of cumenhydroperoxide,and 0.3 parts of t-dodecyl mercaptane chain transfer agent were added.The blend was kept at 75° C. for 5 hours to obtain ABS latex. To the ABSlatex, 1% sulfuric acid was added, coagulated and dried to obtainstyrene-containing graft copolymer resin (g-ABS) in powder form.

(B₂) A graft copolymer of EXL-2602 (product name) by Kureha Co. wasused, in which methacrylic acid ester monomers are grafted ontobutadiene rubber.

(C) Vinyl Copolymer

71 parts of styrene, 29 parts of acrylonitrile, 120 parts of deionizedwater and 0.2 parts of azobisisobutylonitrile (AIBN) were blended. Tothe blend, 0.5 parts of tricalciumphosphate and 0.3 parts ofmercaptan-containing chain transfer agent were added. The resultantsolution was heated to 80° C. for 90 minutes and kept for 180 minutes.The resultant was washed, dehydrated and dried. Styrene-acrylonitrilecopolymer (SAN) was obtained.

(D) Phosphorous Compound

(d₁) Cyclic Phosphazene Oligomer

The cyclic phosphazene oligomer is a mixture of: 66.5% by weight of anoligomer of Formula (I) in which R₁ is phenoxy, k and m are 1 or 2, andn is 0; 20.3% by weight of an oligomer of Formula (II) in which R₁ isphenoxy, R₂ is a derivative from resorcinol, k and m are 1 or 2, and nis 1; 4.9% by weight of an oligomer of Formula (II) in which R₁ isphenoxy, R₂ is a derivative from resorcinol, k and m are 1 or 2, and nis 2; and 8.3% by weight of an oligomer of Formula (II) in which R₁ isphenoxy, R₂ is a derivative from resorcinol, k and m are 1 or 2, and nis 3 or more.

(d₂) Phosphate Ester Morpholide

(d_(2a)) This phosphate ester morpholide contains 9% by weight oftriphenylphosphate (TPP), and 91% by weight of a monophosphate estermorpholide represented by the chemical Formula (II) where R₃ is a phenylgroup, which consists of 88% by weight of the compound of l=1 and x=y=0,and 3% by weight of the compound of l=2 and x=y=0.

(d_(2b)) This phosphate ester morpholide was obtained by reactingresorcinol with phenyl morpholino chlorophosphate and represented by thechemical Formula (II) where R₃ is a phenyl group and R₄ is a resorcinolderivative, containing 1.5% by weight of phosphate ester morpholidewhere l=1 and x=y=0; 68.4% by weight phosphate ester morpholide wherel=1 and x+y=1; and 30.1% by weight phosphate ester morpholide where l=1and x+y=2 or more.

(d₃) Linear Cross-linked Phosphazene

The phosphazene used in the Comparative Examples is a mixture of linearcross-linked phosphazene oligomers. The mixture was prepared to link 62%by weight of phenoxy phosphazene trimer, 12% by weight of phenoxyphosphazene tetramer, and 26% by weight of phenoxy phosphazene pentameror more with hydroquinone. The molar ratio of phenoxy to hydroquinone is1.7 to 0.15 and the weight average molecular weight is about 1100.

(E) Fluorinated Polyolefin Resin

Teflon (registered trademark) 7AJ by Dupont company was used.

Examples 1-6 and Comparative Examples 1-7

The resin compositions of Examples 1-6 and Comparative Examples 1-7 wereprepared as in Tables 1 and 2. The mechanical properties are shown inthe Tables.

Comparative Example 1 was conducted in the same manner as in Example 1except that the phosphorous mixture with the composition out of theclaimed range was used as in Table 2.

Comparative Examples 2-4 were conducted in the same manner as in Example1 except that a single phosphorous compound was used as in Table 2.

Comparative Example 5 was conducted in the same manner as in Example 2except that a linear phosphazene oligomer was used as in Table 2.

Comparative Example 6 was conducted in the same manner as in Example 6except that a phosphate ester morpholide only was used as in Table 2.

Comparative Example 7 was conducted in the same manner as in Example 6except that a linear phosphazene oligomer was used as in Table 2.

The components as shown in Tables 1 and 2, an antioxidant and a heatstabilizer were mixed in a conventional mixer and the mixture wasextruded through a twin screw extruder with L/D=35 and Ø=45 mm at 240°C. to prepare in pellet form. The resin pellets were molded into testspecimens for measuring flame retardancy and mechanical properties usinga 10 oz injection molding machine at 240° C. The specimens were kept atthe relative humidity of 50% at 23° C. for 48 hours. The physicalproperties were measured in accordance with ASTM regulations.

The mechanical properties of the test specimens of Examples 1-6 andComparative Examples 1-7 were measured as follow:

The flexural strength was measured in accordance with ASTM D790.

The flame retardancy was measured in accordance with UL94VB. The testspecimens have a thickness of 1.6 mm.

For each Example, five specimens were tested twice. The total flame outtime is the sum of the first flame out time and the second flame outtime.

The melt flow index was measured in accordance with ASTM D1238 under220° C./10 kgf.

The heat distortion temperature was measured in accordance with ASTMD648 under 18.6 kgf.

TABLE 1 Examples 1 2 3 4 5 6 (A) 80 80 80 80 80 95 (B) (B₁) 10 10 10 1010 — (B₂) — — — — — 5 (C) 10 10 10 10 10 — (D) (d₁) 1 3 5 2 2 1 (d_(2a))2 2 1 — 10 2 (d_(2b)) 9 7 6 10 — 2 (d₃) — — — — — — (E) 0.5 0.5 0.5 0.50.5 0.4 UL94VB ( 1/16″) V-0 V-0 V-0 V-0 V-0 V-0 Total Flame Out Time(sec) 14 17 16 17 11 12 Flexural Strength 845 855 855 850 855 905 HDT 9192 95 96 90 121 MFI 34 32 30 31 35 19

TABLE 2 Comparative Examples 1 2 3 4 5 6 7 (A) 80 80 80 80 80 95 95 (B)(B₁) 10 10 10 10 10 — — (B₂) — — — — — 5 5 (C) 10 10 10 10 10 — — (D)(d₁) 9 12 — — — — — (d_(2a)) 1 — — 12 1 2 2 (d_(2b)) 2 — 12 — 6 3 2 (d₃)— — — — 5 — 1 (E) 0.5 0.5 0.5 0.5 0.5 0.4 0.4 UL94VB ( 1/16″) V-1 V-1V-2 V-1 V-1 V-1 V-1 Total Flame Out Time (sec) 58 69 115 57 69 71 66Flexural Strength 825 815 825 835 835 890 895 HDT 96 101 91 85 94 120120 MFI 24 19 31 35 30 21 21

As shown in Tables 1 and 2, the resin compositions employing aphosphorous mixture of cyclic phosphazene oligomer and phosphate estermorpholide show synergistic effect in flame retardancy and flexuralstrength with no big difference in heat distortion temperature and meltflow index, compared to those employing a single phosphorous compound.The resin composition using a linear phosphazene oligomer shows a poorflame retardancy.

The examples of parent U.S. Pat. No. 7,094,818 in their entirety areherein incorporated by reference.

1. A flame retardant thermoplastic resin composition comprising: (A)about 45 to 95 parts by weight of a polycarbonate resin; (B) about 1 to50 parts by weight of a rubber modified vinyl-grafted copolymer preparedby graft-polymerizing (b₁) about 5 to 95 parts by weight of a monomermixture consisting of about 50 to 95% by weight of at least one selectedfrom the group consisting of styrene, α-methylstyrene, halogen- oralkyl-substituted styrene, C₁₋₈ methacrylic acid alkyl ester, C₁₋₈acrylic acid alkyl ester, and a mixture thereof and about 5 to 50% byweight of acrylonitrile, methacrylonitrile, C₁₋₈ methacrylic acid alkylester, C₁₋₈ acrylic acid alkyl ester, maleic acid anhydride, or C₁₋₄alkyl- or phenyl N-substituted maleimide onto (b₂) about 5 to 95 partsby weight of a rubber polymer selected from the group consisting ofbutadiene rubber, acryl rubber, ethylene-propylene rubber,styrene-butadiene rubber, acrylonitrile-butadiene rubber, isoprenerubber, copolymer of ethylene-propylene-diene (EPDM),polyorganosiloxane-polyalkyl (meth)acrylate rubber and a mixturethereof; (C) about 0 to 50 parts by weight of a vinyl copolymerpolymerized with (c₁) about 50 to 95% by weight of at least one ofstyrene, α-methylstyrene, halogen- or alkyl-substituted styrene, C₁₋₈methacrylic acid alkyl ester, C₁₋₈ acrylic acid alkyl ester or a mixturethereof and (c₂) about 5 to 50% by weight of at least one ofacrylonitrile, methacrylonitrile, C₁₋₈ methacrylic acid alkyl ester,C₁₋₈ acrylic acid alkyl ester, maleic acid anhydride, C₁₋₄ alkyl- orphenyl N-substituted maleimide or a mixture thereof; (D) about 1 to 30parts by weight of a mixture, as a flame retardant, per 100 parts byweight of (A)+(B)+(C), of (d₁) about 1 to 50% by weight of a cyclicphosphazene oligomer compound or mixture thereof represented by thefollowing formula;

where R₁ is alkyl, aryl, alkyl substituted aryl, aralkyl, alkoxy,aryloxy, amino or hydroxyl, k and m are an integer from 1 to 10, R₂ isdioxyarylene group of C₆₋₃₀ or a derivative thereof, and n is 0 or aninteger representing the number of repeating unit and the average valueof n in the phosphazene mixture is 0.3 to 3; and about 99 to 50% byweight of (d₂) or (D₂) wherein (d₂) is a phosphate ester morpholiderepresented by the following formula;

where R₃ is a C₆₋₂₀ aryl group or an alkyl-substituted C₆₋₂₀ aryl group,R₄ is a C₆₋₃₀ arylene group or an alkyl-substituted C₆₋₃₀ arylene group,l is 1 or 2, and x and y are 0 or integers representing the number ofcorresponding units and the average value of (x+y) in the mixture ofphosphate ester morpholide compounds is 0 to 5; (D₂) is a phosphoricacid ester represented by the following Formula (IV);

where R₃, R₄, R₅ and R₇ are a C₆₋₂₀ aryl group or an alkyl-substitutedC₆₋₂₀ aryl group, respectively; R₅ is a C₆₋₃₀ arylene group or analkyl-substituted C₆₋₃₀ arylene group; and l means the number ofrepeating unit and the average value of l in the phosphate mixture is 0to 3; and, (E) about 0.05 to 5.0 parts by weight of a fluorinatedpolyolefin resin with average particle size of about 0.05 to 1000 μm anddensity of about 1.2 to 2.3 g/cm³, per 100 parts by weight of(A)+(B)+(C).
 2. The flame retardant thermoplastic resin composition asdefined in claim 1, wherein said cyclic phosphazene oligomer compoundhas a linear structure or a structure with a branched chain at the mainchain.
 3. The flame retardant thermoplastic resin composition as definedin claim 1, wherein R₁ is phenoxy and R₂ is a derivative from catechol,resorcinol, hydroquinone, or the bisphenylenediol represented by thefollowing formula:

where Y is alkylene of C₁₋₅, alkylidene of C₁₋₅, cycloalkylidene ofC₅₋₆, S or SO₂, and z is 0 or
 1. 4. The flame retardant thermoplasticresin composition as defined in claim 1, wherein said R₃, R₄, R₆ and R₇in Formula (IV) are a phenyl group or an alkyl-substituted phenyl groupwhere the alkyl is methyl, ethyl, isopropyl or t-butyl, and R₅ is aderivative from resorcinol, hydroquinone, or bisphenol-A.
 5. A moldedarticle produced from the flame retardant thermoplastic resincomposition as defined in claim 1.